Apple confirmed on Tuesday that a software issue is disrupting the normal delivery of iMessages, but the company said it was readying a software update to resolve the issue.

For the past several days, iOS 7 users have complained about being unable to send texts on Apple's instant-messaging service, which provides free texting between iOS devices. A frequent complaint is that while messages appear to have been sent successfully, they later appear with an indication that delivery failed.

"We are aware of an issue that affects a fraction of a percent of our iMessage users, and we will have a fix available in an upcoming software update," Apple said in a statement to The Wall Street Journal. "In the meantime, we encourage any users having problems to reference our troubleshooting documents or contact AppleCare to help resolve their issue. We apologize for any inconvenience this causes impacted users."

Since its release on September 18, Apple's completely rebuilt mobile operating system has been praised for its simpler color scheme. But a week later, Apple released a supplemental update to fix a bug that would let users bypass the passcode security on the lock screen.